Re: [PATCH] net: macb: Add big endian CPU support

On Tue, Feb 24, 2015 at 6:27 PM, Nicolas Ferre [off-list ref] wrote:

Le 24/02/2015 08:39, Arun Chandran a écrit :

quoted

This patch converts all __raw_readl and __raw_writel function calls
to their corresponding readl_relaxed and writel_relaxed variants.

It also tells the driver to set ahb_endian_swp_mgmt_en bit in dma_cfg
when the cpu is configured in big endian mode.

Signed-off-by: Arun Chandran <redacted>
---
      This patch is tested on xilinx ZC702 evaluation board with
      CONFIG_CPU_BIG_ENDIAN=y and booting NFS rootfs
      Added on the fly IP endianness detection according to
      comments from Michal Simek.
---
---
 drivers/net/ethernet/cadence/macb.c | 33 +++++++++++++++++++++++++++------
 drivers/net/ethernet/cadence/macb.h | 15 ++++++++-------
 2 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index ad76b8e..1642911 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c

@@ -449,7 +449,7 @@ static void macb_update_stats(struct macb *bp)
      WARN_ON((unsigned long)(end - p - 1) != (MACB_TPF - MACB_PFR) / 4);

      for(; p < end; p++, reg++)
-             *p += __raw_readl(reg);
+             *p += readl_relaxed(reg);
 }

 static int macb_halt_tx(struct macb *bp)

@@ -1578,6 +1578,7 @@ static u32 macb_dbw(struct macb *bp)
 static void macb_configure_dma(struct macb *bp)
 {
      u32 dmacfg;
+     u32 tmp, ncr;

      if (macb_is_gem(bp)) {
              dmacfg = gem_readl(bp, DMACFG) & ~GEM_BF(RXBS, -1L);

@@ -1585,7 +1586,25 @@ static void macb_configure_dma(struct macb *bp)
              if (bp->dma_burst_length)
                      dmacfg = GEM_BFINS(FBLDO, bp->dma_burst_length, dmacfg);
              dmacfg |= GEM_BIT(TXPBMS) | GEM_BF(RXBMS, -1L);
-             dmacfg &= ~GEM_BIT(ENDIA);
+             dmacfg &= ~GEM_BIT(ENDIA_PKT);

I think this will fail... (see below)

quoted

+
+             /* Here we use the loopback bit of net_ctrl register to detect
+              * endianness on IP. save it first. Program swaped mode for
+              * management descriptor accesses if writing to loop back bit
+              * and reading it back brings no change in bit value.
+              */
+             ncr = macb_readl(bp, NCR);
+             __raw_writel(MACB_BIT(LLB), bp->regs + MACB_NCR);
+             tmp =  __raw_readl(bp->regs + MACB_NCR);
+
+             if (tmp == MACB_BIT(LLB))
+                     dmacfg &= ~GEM_BIT(ENDIA_DESC);

Ditto

quoted

+             else
+                     dmacfg |= GEM_BIT(ENDIA_DESC);

Ditto

Actually GEM_BIT(ENDIA_DESC) won't fail as I have defined
GEM_ENDIA_DESC_OFFSET. But I failed to notice others (GEM_BF*)

I will send another version. Thank you for spotting it.

--Arun